This invention relates to a sprocket assembly with replaceable teeth and, more particularly one wherein the securement of the teeth not only is substantially free of chain stress but further cooperates with the force of the chain in enhancing the tooth securement.
Although the sprocket assemblies of the invention have wide application, they are particularly suited for use in pulp mill conveyors where the wearing stresses are extraordinary. This has necessitated the use of very large sprockets of the order of 25" pitch diameters (632 mm). Thus, sprocket replacement is costly and time-consuming.
The instant invention provides three significant advantages over prior sprocket assemblies employed in the pulp mill arduous operation: (1) the ability of tooth replacement without disassembly of the chain and sprocket, (2) the operation of the assembly without stress on the tooth lock, and (3) the ability to provide both the teeth and the sprocket without machining--except for the sprocket bore.
The first advantage has been long known--see for example U.S. Pat. Nos. 259,875; 358,771; 1,206,172 and 1,630,313. However, none of these achieve the additional advantages of the invention and further, notwithstanding the long availability of structures teaching the advantage of replacement without chain disassembly, this is has not been realized in the intervening art as exemplified by U.S. Pat. Nos. 2,863,323; 3,311,220; 3,439,555 and 4,109,545.
The instant invention achieves these cooperative advantages by utilizing a replaceable tooth having inward of the usual chain engaging contour, a circumferentially related toe part and heel part for mounting within a pocket inward of the periphery of the generally cylindrical sprocket. Lock means are provided in axial passages in the sprocket associated with the heel part so that the chain force and lock force both cooperate to firmly seat the tooth toe part within the pocket and thus relieve the lock any function except to maintain the tooth on the sprocket when there is no chain force.
Other objects and advantages of the invention may be seen in the ensuing specification.